Retinoids (e.g. Vitamin A and its derivatives) are substances which are known to have a broad spectrum of biological activity. More specifically, these substances affect cell growth, differentiation and proliferation. Retinoids affect the differentiation, maintenance, and proliferation of many types of cells, whether they are of ectodermal, endodermal or mesodermal origin. Retinoids have found clinical utility in the treatment of acne vulgaris, severe cystic acne, psoriasis, and other disorders of keratinization. Possible uses of retinoids are being explored in the prophylaxis and treatment of cancer. See generally, Pawson, B. A. et al., "Retinoids at the Threshold: Their Biological Significance and Therapeutic Potential", Journal of Medicinal Chemistry 25:1269-1277 (1982).
It is known to use certain retinoids, particularly tretinoin, topically for treatment of acne as set forth in U.S. Pat. No. 3,729,568. Other known topical uses of tretinoin include, in addition to ache treatment, treatment of senile comedones, nevus comedonicus, linear verrucous nevus, plantar warts, pseudofolliculitis, keratoacanthoma, solar keratosis of extremities, callosities, keratosis palmaris et plantaris, Darier's disease, ichthyosis, psoriasis, acanthosis nigricans, lichen planus, molluscum contagiosum, reactive perforating collagenosis, melasma, corneal epithelial abrasion, geographic tongue, Fox-Fordyce disease, cutaneous metastatic melanoma and keloids or hypertrophic scars see, e.g., Thomas, J. R., et al., "The Therapeutic uses of Topical Vitamin A Acid", Journal of American Academy of Dermatology 4:505-516 (1981).
U.S. Pat. No. 4,603,146 discloses methods for treating sundamaged human skin topically with tretinoin in an emollient vehicle. U.S. Pat. Nos. 4,877,805 and 4,883,342 disclose methods for the treatment of sundamaged human skin using retinoids. U.S. Pat. No. 5,051,449 discloses treatment of cellulite with retinoids.
The above-noted patents disclose formulations of retinoids in various moisturizing bases such as creams or ointments. Retinoids, such as tretinoin, in cream formulations, may meet the needs of certain individuals but may be found undesirable by other individuals. It is also suggested in European Patent Application No. 90303826.3 to Maxam, Inc. that volatile vehicles, such as alcohols, which may dry or otherwise harm the skin should be avoided. Maxam's patent application discloses an aqueous gel formulation of tretinoin which utilizes a glycerin and a proteinaceous material, e.g. soluble animal collagen, to stabilize its gelling agent. The present invention does not require the use of glycerin nor a proteinaceous material to stabilize its gel formulation.